webrick: httpauth requires regular files

Be sure we do not try to open a pipe to read from, since we care
about mtime in all cases.

* lib/webrick/httpauth/htdigest.rb: use File.open
* lib/webrick/httpauth/htgroup.rb: ditto
* lib/webrick/httpauth/htpasswd.rb: ditto
  [Misc #14216]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@61397 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

lib/webrick/httpauth/htdigest.rb

@@ -40,7 +40,7 @@ module WEBrick
         @digest = Hash.new
         @mutex = Thread::Mutex::new
         @auth_type = DigestAuth
-        open(@path,"a").close unless File::exist?(@path)
+        File.open(@path,"a").close unless File.exist?(@path)
         reload
       end
 
@@ -51,7 +51,7 @@ module WEBrick
         mtime = File::mtime(@path)
         if mtime > @mtime
           @digest.clear
-          open(@path){|io|
+          File.open(@path){|io|
             while line = io.gets
               line.chomp!
               user, realm, pass = line.split(/:/, 3)

lib/webrick/httpauth/htgroup.rb

@@ -36,7 +36,7 @@ module WEBrick
         @path = path
         @mtime = Time.at(0)
         @group = Hash.new
-        open(@path,"a").close unless File::exist?(@path)
+        File.open(@path,"a").close unless File.exist?(@path)
         reload
       end
 
@@ -46,7 +46,7 @@ module WEBrick
       def reload
         if (mtime = File::mtime(@path)) > @mtime
           @group.clear
-          open(@path){|io|
+          File.open(@path){|io|
             while line = io.gets
               line.chomp!
               group, members = line.split(/:\s*/)

lib/webrick/httpauth/htpasswd.rb

@@ -40,7 +40,7 @@ module WEBrick
         @mtime = Time.at(0)
         @passwd = Hash.new
         @auth_type = BasicAuth
-        open(@path,"a").close unless File::exist?(@path)
+        File.open(@path,"a").close unless File.exist?(@path)
         reload
       end
 
@@ -51,7 +51,7 @@ module WEBrick
         mtime = File::mtime(@path)
         if mtime > @mtime
           @passwd.clear
-          open(@path){|io|
+          File.open(@path){|io|
             while line = io.gets
               line.chomp!
               case line